element-plus/docs/examples/message/raw-html.vue

<template>
  <el-button :plain="true" @click="openHTML">Use HTML String</el-button>
</template>

<script lang="ts">
import { defineComponent } from 'vue'
import { ElMessage } from 'element-plus'

export default defineComponent({
  setup() {
    const openHTML = () => {
      ElMessage({
        dangerouslyUseHTMLString: true,
        message: '<strong>This is <i>HTML</i> string</strong>',
      })
    }
    return {
      openHTML,
    }
  },
})
</script>